JPH0353124A - Flow meter - Google Patents

Abstract

PURPOSE:To improve stability for a long time by measuring flow by the use of differential pressure in an pressure tap. CONSTITUTION:The flow is measured by utilizing that the flow velocity of fluid in a bypass passage 5 corresponds to pressure P1 in a main passage, pressure P2 in a nozzle 3 and the differential pressure P1-P2. Namely, the flow which passes the nozzle 3 is indirectly measured. Thus, the stability is improved for a long time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a flowmeter using a microbridge,
In particular, it relates to fluidic flowmeters that measure even low flow rates.

[Conventional technology]

It is conceivable to use a microbriefage to measure low flow rates in a fluid ink flow meter, but the fluid to be measured may contain dust or ξ dust.

[Problem to be solved by the invention]

Conventional flowmeters have a problem in that when the fluid to be measured contains dust or mist, these particles hit the microbridge chip, causing the output signal of the microbridge as a flow rate sensor to drift.

Additionally, it is difficult to install the flow rate sensor board inside the nozzle, and a flowmeter that is easy to install has been desired. [Means for Solving the Problems] In order to solve such problems, the first invention of the present invention provides a fluidic flowmeter lid having a pressure extraction hole, a bypass flow path, and a sensor board mounting groove; a flow housing disposed in the bypass flow path and having a flow path narrower than the bypass flow path; a sensor board having a microbriefage chip for detecting the flow velocity in the narrow flow path and a pin for external connection;
A gasket that prevents fluid from leaking to the outside, a sealing material that prevents fluid from leaking to the pin, and a bypass flow path lid that fixes the gasket to the fluid ink flow meter lid are provided. The flow rate in the main flow path is measured by using a microbridge to measure the minute flow rate flowing into the bypass flow path due to the differential pressure.

Further, as a second invention, in the above invention, the cross-sectional area of the narrow flow path of the flow housing is larger at the entrance and exit, and is smaller at the center than at the entrance and exit.

[Function] In the flowmeter according to the present invention, the amount of dust and mist that hits the microbridge chip is extremely small, and the sensor board can be easily attached.

〔Example〕

FIG. 3 is a cross-sectional view showing a general fluidic flowmeter, in which 1 is a fluidic flowmeter and F is an arrow indicating the direction of fluid flow.

FIG. 1 is an explanatory diagram for explaining the principle of the present invention,
A cross section taken along line I-1 in FIG. 3 is shown. In Figure 1,
2 is a micro bridge chip, 3 is a nozzle, 4 is a main channel, 5 is a bypass channel, 6 is a lid of a fluidic flowmeter,
F is an arrow indicating the direction of fluid flow. In the flowmeter according to the present invention, the fluid flow rate in the bypass flow path 5 is determined by the pressure difference P between the pressure P1 in the main flow path and the pressure P2 in the nozzle 3.
1-P2, and indirectly measures the flow rate passing through the nozzle 3. Figure 2 shows a case where a bypass flow path 5 is provided in the fluid ink body, and the principle is the same as that in Figure 1. 4 to 7 are structural diagrams showing the structure of a first embodiment of a flowmeter according to the present invention. In Figures 4 to 7, 2
1 is a microbridge chip that detects the flow velocity, 7 is a sensor substrate (for example, a ceramic thick film wiring board or printed circuit board), 7a is a pin, 8 is a flow housing, 9 is a flow path, 1
0 is a pressure outlet hole, 11 is a sensor board mounting groove, 12 is a punch hole, 13 is a lid for a bypass flow path, 14 is a gasket made of a rubber plate or cork, etc., 15 is a sealing material such as grease or epoxy, and 16 is a sealing material such as grease or epoxy. The screw 17 is a groove for a pin. Figure 5 shows a sensor unit that integrates the sensor board 7 and flow housing 8, and Figure 6 shows the lid of the fluidic flowmeter. In this embodiment, the sensor unit shown in FIG.
It is manufactured by assembling it into the lid shown in the figure as shown in FIG. That is, first, the sensor unit shown in FIG. 5 is attached to the bypass channel 5, and the vicinity of the pin 7a is covered with a sealing material 15 to prevent fluid from leaking to the pin 7a side.

Next, the gasket 14 is placed at a predetermined position, and the gasket 14 is fixed to the lid 6 using the bypass channel lid 13.

8 to 12 are structural diagrams showing a second embodiment of the present invention. Figures 8 to 10 show examples of sensor units. 8 and 9 show an example in which the pin 7a is placed on the flow housing 8 side, and FIG. 10 shows an example in which the pin 7a is placed on the sensor board 7 side.
Indicates the case where .

FIG. 11 shows lI6 according to the sensor unit of FIGS. 8 to 10. The difference from FIG. 6 is that there is no pin groove l7 and that there is an opening 18. Opening 18 is pin 7
This is for connecting a to an external connector, etc.

If the flow housing 8 is shortened in the flow direction as shown in Fig. 1.3, or narrowed only near the micro bridge chip as shown in Fig. 14 (al to (C)),
The pressure drop in the bypass channel becomes smaller, the amount of flow diverted increases, and the flow velocity in the microbridge chip portion becomes faster, so the output signal from the sensor unit becomes high level.

As shown in FIG. 15, a flow housing is built into the lid 6 of the fluid ink flowmeter, and a sensor base F is attached to it.
You can also install i7. Also, to take out the lead wire,
You can use the connector 19 as shown in FIG.
It can also be attached directly to the circuit board 20 as shown in FIG.

Furthermore, if the lid 6 of the fluid ink flowmeter is processed as shown in FIG. 18, there is no need to bend the pin 7a of the sensor board as shown in FIG. In the above embodiment, the sensor unit was incorporated into the lid 6 of the fluid ink flowmeter, but as shown in FIGS. 19 and 20,
The fluid may be guided to the bypass channel 5 by the tube 22 and the coupling 23 or joint 24.

〔Effect of the invention〕

As explained above, the present invention measures the flow rate by measuring the differential pressure generated between the upstream side of the nozzle and the interior of the nozzle or the downstream side of the nozzle using a microbridge chip in the bypass flow path. The amount of dust and mist that hits the microbridge chip can be greatly reduced, which has the effect of improving long-term stability. Furthermore, since there is no need to attach the sensor board inside the nozzle, there is an effect that the sensor board can be easily attached.

[Brief explanation of drawings]

1 and 2 are explanatory diagrams for explaining the principle of the present invention, FIG. 3 is a sectional view showing a general fluidic flowmeter, and FIGS. 4 to 7 are diagrams showing the flowmeter according to the present invention. Figures 8 to 12 are diagrams showing the configuration of the second embodiment of the present invention, and Figures 13 and 14 are diagrams showing the configuration of the sensor unilateral sensor. 15 to 18 are configuration diagrams showing other embodiments, and FIGS. 19 and 20 are configuration diagrams showing a case where a bypass flow path is provided externally. 2... Micro bridge chip, 3... Nozzle, 4
...Main flow path, 5...Bypass flow path, 6...Lid of fluidic flowmeter, 7...Sensor board, 7a...
Pin, 8... Flow housing, 9... Channel, 10
...Pressure outlet hole, 11...Sensor board mounting groove, 12
...Screw hole, 13...Bypass channel cover, 14...
・Gasket, 15... Sealing material, 16... Screw, 17... Pin groove.

Claims (2)

[Claims] (1) A lid of a fluidic flowmeter having a pressure outlet hole, a bypass flow path, and a sensor board mounting groove; a flow housing disposed in the bypass flow path and having a flow path narrower than the bypass flow path; A sensor board that has a thermal flow velocity sensor such as a microbridge chip that detects the flow velocity of a flow path, a pin for external connection, a gasket that prevents fluid from leaking to the outside, and a fluid leakage to the pin portion. A flowmeter that measures the flow rate based on the differential pressure in the pressure extraction hole, the flowmeter comprising a sealing material that prevents the gasket from leaking, and a bypass flow path lid that fixes the gasket to the lid of the fluidic flowmeter. (2) The flowmeter according to claim 1, wherein the cross-sectional area of the narrow channel of the flow housing is larger at the entrance and exit, and smaller at the center than at the entrance and exit.